Wandering at night, agitation, disturbed sleep and night/day reversal are common problems for demented elderly and often lead to institutionalization. Learning more about the correlates of agitation, wandering and sundowning and their relation to sleep, and examining techniques to improve these symptoms might postpone, if not avoid, institutionalization. Our interest in agitation grew out of our prior years of experience working with nursing home patients. In the process of examining the effect of light treatment on sleep consolidation, we observed the effect light seemed to have on behavior. We now propose to study agitation more systematically and examine a behavioral treatment designed to attenuate agitated behavior. Our specific aims are to 1) evaluate the effect of light therapy on agitated behavior; 2) determine within patients the degree of agitation occurring at night vs. that occurring during the day; 3) determine the percent of patients with primarily evening agitation and the percent with primarily morning agitation; 4) examine the relationship between agitated behaviors and light exposure; 5) examine the relationship between agitated behaviors and sleep; 6) examine the relationship between agitated behaviors and sleep disordered breathing. Each patient will have sleep/wake behavior and light exposure measured with an Actillume recorder; each will have sleep, breathing and blood oxygen saturation levels recorded for one night; each will have agitation measures recorded four times an hour for 24-hour periods. Data for the aims 2-6 will be collected before intervention begins. Patients will then be randomly assigned to one of three treatment groups: Bright light exposure in the morning, dim light exposure in the morning or bright light exposure in the evening. The intervention trials will help determine whether agitation can be reduced by these approaches. The results will both help us understand the correlates of agitation and suggest treatment options.